Alcohol consumption, neuropsychological status and computer-tomographic findings in a random sample of men and women from the general population

PharmacologyBiochemistry&Behavior, Vol. 18, Suppl. 1, pp. 501-505, 1983. ('' Ankho International. Printed in the U.S.A.

Alcohol Consumption, Neuropsychological Status and Computer-Tomographic Findings in a Random Sample of Men and Women from the General Population HANS

BERGMAN,

2 GORAN

AXELSSON,

C.-M. I D E S T R O M

Department o f Clinical Alcohol- and Drug Research, Karolinska blstitute, S-104 O1 Stockholm, Sweden STEFAN

BORG

Department of Psychiatry, St. G/Jran's Hospital, S-112 81 Stockholm, Sweden TOMAS

HINDMARSH

Department of Radiology, Dandervds ltospital, S-182 88 Danderyd, Sweden JOSEF

MAKOWER

Department o f Radiology, Karolinska ttospital, S-104 Ol Stockholm, Sweden AND STURE

MOTZELL

Department of Internal Medicine, KiJping Hospital, S-731 Ol KiJping, Sweden

BERGMAN, H., G. AXELSSON, C.-M. IDESTROM, S. BORG, T. HINDMARSH, J. MAKOWER AND S. MI21TZELL. Alcohol consumption, neuropsychological status and computer-tomographicfindings in a random sample of men and womenfrom the generalpopulation. PHARMACOL BIOCHEM BEHAV 18: (Suppl. 1,501-505, 1983.--There was no correlation between reported amount of alcohol consumed on each drinking occasion per se and neuropsychological and neuroradiological signs of cerebral disorder in age-stratified random sample of 200 men and 200 women taken from the general population. Furthermore, moderate to heavy social drinking as assessed by an index based on amount of alcohol consumed on each drinking occasion and the responses to some other alcohol-habit questions was not associated with signs of cerebral disorder. Alcohol dependence, however, was associated with signs often diagnosed in alcoholic patients but milder in degree. There were indications of important differences between men and women with regard to the relationship between advanced alcohol-habits and cerebral disorder. Alcohol consumption Computer tomography

Alcohol abuse

Brain damage

T H E results f r o m m a n y e m p i r i c a l studies c a r r i e d o u t in diff e r e n t l a b o r a t o r i e s a n d clinical s e t t i n g s s p e a k in f a v o r o f a r e l a t i o n s h i p b e t w e e n c h r o n i c a l c o h o l i s m a n d c e r e b r a l disorder. P a r t i c u l a r l y d u r i n g the last few years, n e u r o r a d i o l o g i c a l a n d n e u r o p s y c h o l o g i c a l studies h a v e s h o w n t h a t a n a t o m i c a l c e r e b r a l c h a n g e s a n d n e u r o p s y c h o l o g i c a l deficits c a n o f t e n b e d i a g n o s e d in a l c o h o l i c p a t i e n t s w i t h o u t clinically e v i d e n t s y m p t o m s o f c e r e b r a l d i s o r d e r (see [17] for a r e c e n t review).

Cerebral disorder

Neuropsychological deficit

T h u s , m a n y alcoholic p a t i e n t s h a v e m o r p h o l o g i c a l cerebral c h a n g e s w h e n e x a m i n e d with c o m p u t e d t o m o g r a p h y o f the b r a i n a p p e a r i n g as a n e n l a r g m e n t of the v e n t r i c u l a r syst e m , particularly the 3rd v e n t r i c l e , a n d as a w i d e n i n g o f cortical sulci. T h e s e c h a n g e s h a v e b e e n i n t e r p r e t e d as i n d i c a t i n g c e n t r a l a n d cortical a t r o p h y o f t h e brain. W i d e n e d cortical sulci are often o b s e r v e d e v e n in quite y o u n g alcoholic p a t i e n t s , b e l o w t h e age o f thirty, while

'Supported by grants from the Swedish Welfare Department and the Bank of Sweden Tercentenary Foundation. ~To whom requests for reprints should be addressed.

501

502

BERGMAN E T A L .

enlargement of the ventricular system is more often diagnosed in older alcoholics with a long duration of heavy drinking. Furthermore, such cortical and ventricular changes seem to follow different courses and they correlate with somewhat different patterns of neuropsychological deficits [3-6]. Neuropsychological studies of such patients have shown an increased incidence of intellectual impairment, particularly with regard to abstracting and problem-solving abilities when dealing with visuo-spatial tasks. Long-term memorydependent abilities and sensory or motor functions are less often impaired [5,15]. The correlation between morphological cerebral changes and neuropsychological deficit is generally modest with the possible exception of old alcoholics who often have clinically manifest symptoms of cerebral disorder [2-4, 6]. Furthermore, in some studies using the partial correlation technique, the relationship is to a great extent explained by chronological age [4,6]. However, in partial correlations some of the covariance which is actually due to the duration of heavy drinking per se is taken away. It is difficult to distinguish between heavy social drinking and alcoholism and it seems reasonable that there might be a continuum of cerebral disorder in connection with advancing alcohol habits. This continuum would go from nonimpaired low consumers of alcohol or abstainers, through an unkfiown degree of morphological cerebral changes and neuropsychological deficit in moderate or heavy social drinkers and alcohol dependents in the general population to diagnosed cerebral disorder in alcoholic patients. Unfortunately, very little research on cerebral disorder in social drinkers taken from the general population has been carried out. However, in two studies a correlation between amount of alcohol consumed per drinking occasion and impaired neuropsychological performance in selected social drinkers was reported [13,14]. The purpose of the present study was to investigate a possible relationship between alcohol habits and cerebral disorder in the general population while controlling for the confounding influences of chronological age and formal education for each sex. METHOD

A sample of 200 men and 200 women was randomly drawn from the general population of a defined geographical area in Stockholm. The dropout was less than 10% in the male group and about 15% in the female. The sample was drawn from a National Register covering all Swedish inhabitants according to a two-stage plan to achieve a rectangular age distribution between 20 and 65 yrs for each sex [6]. Because of mental retardation, alcohol intoxication (one person), language difficulties or lack of motivation, five men and eight women were not psychologically investigated. There was an additional loss of a few persons in the computertomographic examination. The general medical examination included an assessment of neurological status. Tests of blood and urine were also taken. The medical case history and a social anamnesis were taken by means of the same standardized procedures as had been used for alcoholic patients taking part in the KARTAD project (see below). Some data from official registers was also collected. The psychological examination included a comprehensive neuropsychological assessment including the Halstead Rei-

tan test battery. For further details see [3,7]. Raw scores were transformed into T-scores, i.e., the mean was set to 50 and the standard deviation to 10 for each test, based on the results of the sample separated into three age intervals and two levels of formal education [7]. By means of this double standardization technique, satisfactory control over the influence of age- and education differences was achieved. Both these variables are highly correlated with performance on most neuropsychological tests [7,10]. The computed-tomography investigation included an assessment of the width of the lateral ventricles and the third ventricle, for further details see [3]. The same kind of T-score standardization as was carried out for the neuropsychological tests was also done for the two ventricular measures with regard to chronological age, separately for each sex. Widened cortical sulci was assessed by means of a 4-step rating scale which was left unstandardized. The alcoholic patients of the KARTAD project [1, 8, 9, 11] were used as a comparison group. In the KARTAD project more than 700 consecutively admitted alcoholic patients living in the same geographical area as the random sample were investigated. The data was fed into the computer to create a vast interdisciplinary data bank on alcoholism. Every second KARTAD patient was examined with the same psychological test battery of sensory, motor, intellectual and personality functioning as the random sample [1,7]. During a 2-year period they were also investigated with computed tomography of the brain in the same way as the random sample. RESULTS

The reported amount of alcohol consumed on one occasion expressed in terms of grams of absolute alcohol usually consumed per day when drinking the most is shown in Fig. 1, separately for the men and the women. The median amount was 16 g for the men and 15 g for the women. Disregarding those who denied alcohol consumption altogether, the median amount was 30 g for both sexes, corresponding to halfa bottle of light wine. There was no correlation between the alcohol consumption variable and neuropsychological test results or computer-tomographic findings when analyzed separately for each sex, irrespective of the exclusion of subjects consuming less than 30 g. However, in order to get an index of advancing alcohol habits a Guttman scalogram analysis was carried out [16] on the consumption variable dichotomized at 30 g and the responses to some drinking-habit questions. The questions concerned experienced loss of control over drinking, taking morning drinks and having had blackouts. A 5-step scale which satisfied the psychometric criteria of unidimensionality and cumulativeness could be constructed for each sex, i.e., persons who responded positively to an advanced habit as a rule also responded positively to the less advanced. The male drinking habit scale is shown in Fig. 2. The female scale was identical except that morning drinks and blackouts changed places. One-hundred and fourteen men who scored 0 on the drinking habit scale since they responded negatively to all the questions were called "low consumers." Sixty-nine scored 1 or 2, i.e., as a rule reported a daily consumption level of at least 30 g and in about 20 cases in combination with subjective loss of control were called "advanced consumers." Thirteen men scored 3 or 4 since they responded positively to either or both of the most advanced drinking-

ALCOHOL,

NEUROPSYCHOLOGY

AND CT-SCANN1NG

503 Scale score L-

No of subjects

12°t II 1101009080706050z,03020100

•

Blackouts

Men 3 -

I Morning d r i n k s 2 S u b j e c t i v e toss of control 1 "High" a l c o h o l c o n s u m p t i o n (-~30gl

Gabs 0-19 20-39 40-59 60-124125-249 250 -< atc./day

FIG. I. Quantity of reported daily alcohol consumption when drinking the most, in grammes of absolute alcohol per day in a random sample of 200 men and 200 women taken from the general population of Stockholm.

h a b i t s , i.e., m o r n i n g d r i n k s a n d b l a c k o u t s . T h e y w e r e called "alcohol dependents." T h e " a d v a n c e d c o n s u m e r s " were y o u n g e r t h a n the o t h e r g r o u p s a n d t h o s e w h o r e p o r t e d loss of c o n t r o l h a d experie n c e d it since 10 yrs o n the average (see T a b l e 1). T h e " a l c o hol d e p e n d e n t s " w e r e o l d e r a n d less f o r m a l l y e d u c a t e d t h a n the o t h e r s . T h e i r daily c o n s u m p t i o n level w h e n d r i n k i n g t h e m o s t c o r r e s p o n d e d to o n e 75 cl b o t t l e o f light wine. T w o m e n o f t h e " a d v a n c e d c o n s u m e r s " a n d o n e o f the " a l c o h o l dep e n d e n t s " r e p o r t e d p r e v i o u s h o s p i t a l t r e a t m e n t for alcohol p r o b l e m s . A s e x p e c t e d , a c t i o n s from the T e m p e r a n c e B o a r d a n d p a t h o l o g i c a l g a m m a g l u t a m y l t r a n s f e r a s e values (S-GT) w e r e m o r e c o m m o n in this g r o u p t h a n in t h e t w o less adv a n c e d (see T a b l e 1).

FIG. 2. Cumulative Guttman scale of alcohol-habits in the male random sample.

W h e n we c o m p a r e d the " a d v a n c e d c o n s u m e r s " with the " l o w c o n s u m e r s " in t e r m s o f age- a n d e d u c a t i o n - s c a l e d n e u r o p s y c h o l o g i c a l test results a n d age- a n d sex-scaled c o m p u t e r - t o m o g r a p h i c m e a s u r e m e n t s , no deficit w h a t s o e v e r was o b s e r v e d . T h u s , no r e l a t i o n s h i p b e t w e e n m o d e r a t e to h e a v y social d r i n k i n g a n d signs o f c e r e b r a l d i s o r d e r was obs e r v e d . H o w e v e r , w h e n the " a l c o h o l d e p e n d e n t s " w e r e c o m p a r e d with t h e " l o w c o n s u m e r s " in a series o f t - t e s t s , a t r e n d of n e u r o p s y c h o l o g i c a l deficit a n d e n l a r g e d v e n t r i c l e s was o b s e r v e d . T h i s t r e n d was statistically significant in logical r e a s o n i n g ( o < 0 . 0 5 ) . T h e age- a n d e d u c a t i o n - s c a l e d results o f t h e male " a l c o h o l d e p e n d e n t s " are plotted in Fig. 3. H o w e v e r , only t h o s e n e u r o p s y c h o l o g i c a l f u n c t i o n s are s h o w n w h i c h often are impaired in alcoholic patients [2, 5, 15]. F o r r e a s o n o f c o m p a r i s o n we h a v e also p l o t t e d the results o f male a l c o h o l i c K A R T A D patients. B u t for the h i g h e r

TABLE l SOME SOCIAL AND MEDICAL CHARACTERISTICS OF MALE A N D FEMALE ALCOHOL-HABIT GROUPS RANDOMLY DRAWN FROM THE GENERAl.. POPULATION Male Alcohol-Habit Groups

Chronological age, Mdn. Secondary school or higher Employed at least 16 hrs/week Alcohol consumption when drinking the most in g absolute alcohol day, Mdn. Duration of subjective loss of control Pathological S-GT* (>1.0/xCat/I) Actions from the Temperance Board

Female Alcohol-Habit Groups

"Low consumers" (N 114)

"'Advanced consumers" (N=69)

"Alcohol dependents" (N=13)

"Low consumers" (N 127)

"Advanced consumers" (N-46)

"Alcohol dependents" (N=18)

48 yrs 50 % 85 % 6g

41 yrs 53 c~ 82 % 37 g

55 yrs 15 % 69 cA 57 g

49 yrs 35 cA 75 % 7g

42 yrs 46% 91% 49 g

36 yrs 56 % 67 % 51g

--

10 yrs

15 yrs

--

--

6 yrs

11%

14 ~

46 %

--

--

--

8%

17 %

38 %

0%

4%

11%

*Since S-GT (gammaglutamyltransferase) is an unreliable indicator for heavy drinking in women it is not tabulated for the female alcohol-habit groups.

504

BERGMAN E T A L . Non-normahzed 36

38

40

42

T-scores

4/~

46

48

NOn normalized

50

Logical reasoning

36

3B

~0

42

T-scores

/*4

L6

~8

SO

Logical reasoning

Vlsuo-spahaL pattern reproduction

Visuo-spatial pattern reproduction

Vlsuo graphic short-term memory

Vlsuo graphic short term memory

A b s t r a c t i n g ability

Abstract mg ability

Tactua[ performance

factual performance

Vlsuo-spahal scannmg and flexlbihty

V~suo spatial scanning and flexibility

Width of latera( ventrictes. reversed scare

Widlh of lateral ventricles, reversed scare

Width of 3rd ventricle, reversed scare

Width of 3rd ventricle, reversed scale

FIG. 3. Neuropsychological and computer-tomographic profiles of 13 randomly selected male -alcohol dependents" from the general population (- - -)and 247 male alcoholic patients (--). The right most vertical line below number 50 corresponds to the value of the whole male random sample. The further to the left of this line, i.e., the lower the T-score, the more neuropsychological deficit and wider ventricles.

level, the profile of the "alcoholic dependents" does not deviate much from that of the alcoholic KARTAD patients, but the non-impaired abstracting ability and tactual performance should be noted. The greatly enlarged 3rd ventricle of the KARTAD patients should also be noted. It was found that an unproportionately high number of the "alcohol dependents" had widened cortical sulci. However, since this analysis was performed on unstandardized scores, the subjects were older than the 'qow consumers" and the fact that there is a correlation between advancing age and sulcal width in the general population [6] this finding should be interpreted with caution. One-hundred and thirty-two women responded negatively to all the alcohol-habit questions of the Guttman scale and were thus called "low consumers." Forty-seven who scored 1, i.e., reported a consumption level of 30 g or more, were called "advanced consumers." Eighteen who scored 2 or more, i.e., responded positively also to the loss of control question and in a few cases also to the more advanced questions concerning morning drinks and blackouts, were called "'alcohol dependents." One woman in this group reported previous hospital treatment for alcohol problems. The female "alcohol dependents" were younger and better educated than the less advanced women. When we compared the female "advanced consumers" with the "low consumers" in a series of t-tests, no signs of any kind of deficit were observed. But when we compared the "'alcohol dependents" with the "low consumers" a trend of neuropsychological deficit but not of ventricular enlargement was observed (see Fig. 4). This trend was statistically significant (p<0.05) in verbal learning (not shown in Fig, 4), and approached significance in logical reasoning ability. However, the deficit was very much less than that observed in the female KARTAD patients. DISCUSSION

There was no correlation between amount of alcohol consumed on each occasion and neuropsychological or neuroradiological signs of cerebral disorder in an agestratified random sample of 400 men and women from the

53

FIG. 4. Neuropsychological and computer-tomographic profiles of 18 randomly selected female "'alcohol dependents" from the general population (- - -) and 75 female alcoholic patients (--).

general population. Such a correlation with regard to neuropsychological deficit was reported by Parker et al. [13,14]. However, their samples of 45 and 102 male social drinkers were not representative of the general population, no neuroradiological examination was performed and there were important methodological differences. In the present study, a cumulative scale of advancing alcohol-habits was constructed, based on reported daily alcohol consumption when drinking the most, and the responses to some other alcohol-habit questions. On the basis of the scale scores the sample was divided into "low consumers," "'advanced consumers" and "'alcohol dependents," separately for men and women. The "advanced consumers" and the "alcohol dependents" were compared with the "'low consumers." The results indicated that alcohol dependence but not moderate to heavy drinking in the general population is associated with slight neuropsychological and neuroradiological signs of cerebral disorder. Stated differently, even a comparatively high level of alcohol consumption per se does not seem to be associated with cerebral disorder. Only in combination with such alcoholic behaviors as having blackouts and/or taking morning drinks is such an association observed. Thus, alcohol-dependent persons appear to have the same symptoms of cerebral disorder but to a lesser degree than those often diagnosed in medically treated alcoholics. The results also indicated sex differences in this regard, since the morphological cerebral changes observed in the male "alcohol dependents" were not evident in the female despite a trend of neuropsychological deficit. However, the less advanced alcohol dependency in the female sample than in the male should be considered. Of course, the responses to drinking-habit questions cannot always be taken at face value. However, in order to make the data as reliable as possible, a combination of questionnaires and interviews was used. This data collection procedure was found to be satisfactory in a project where more than 700 alcoholic patients were investigated in our department [ 12]. There is a correlation between advancing chronological age and neuropsychological impairment, sulcal widening of the cortex and ventricular enlargement [6]. Furthermore, neuropsychological performance is correlated with formal education and ventricular size with sex (the diameter of the

ALCOHOL,

NEUROPSYCHOLOGY

AND CT-SCANNING

3rd ventricle was 4.7 m m in the male and 3.9 m m in the female, a highly significant difference, t(343)=5.42, p < 0 . 0 0 1 ) . S i n c e alcohol h a b i t s are c o r r e l a t e d with age, a n d a l c o h o l i c s o f t e n are less f o r m a l l y e d u c a t e d t h a n n o n a l c o h o l i c s , age-, sex- a n d e d u c a t i o n - d i f f e r e n c e s s h o u l d b e c o n t r o l l e d for in the p r e s e n t t y p e o f studies. H e r e , a satisfactory c o n t r o l was a c h i e v e d b y using n o r m g r o u p - b a s e d T-scores. T h e fact t h a t the ~'alcohol d e p e n d e n t s " o f t h e p r e s e n t study, at least the male, e v i d e n c e d signs o f c e r e b r a l d i s o r d e r o f c o u r s e c a n n o t rule o u t the possibility t h a t the s u s p e c t e d d i s o r d e r in s o m e o f t h e s u b j e c t s might h a v e a n t e d a t e d the advanced alcohol-habits instead of being a probable conseq u e n c e o f t h e m . A s we h a v e d i s c u s s e d e l s e w h e r e [3], r e p o r t s

505

o f c o r r e l a t i o n s b e t w e e n t h e h y p e r a c t i v e child s y n d r o m e a n d a l c o h o l i s m l a t e r in life m a k e s this h y p o t h e s i s plausible. O f c o u r s e , it c a n n o t b e ruled out t h a t the s u g g e s t e d mild cerebral d i s o r d e r m i g h t also b e d u e to u n d i a g n o s e d p a t h o l o g i c a l p r o c e s s e s w h i c h are related to, but n o t c a u s e d by, the n e u r o t o x i c effects o f alcohol a b u s e p e r se in s o m e o f the subjects. ACKNOWLEDGEMENTS We are grateful to Inger Bergman, Karin Engelbrektson, Lena Holm and Staffan Lindberg for making psychological assessments and to Martin Vivaldi who participated in the computer-tomographic assessments.

REFERENCES 1. Bergman, H. The Karolinska project for research and treatment of alcohol dependence (KARTAD). IV: Psychological aspects. In: Recent Advances in the Study o f Alcoholism. Proceedings, first international Magnus Huss symposium, Stockholm, 1976. Excerpta Medica International Congress Series 407, edited by C.-M. Idestrrm. Amsterdam: Excerpta Medica, 1977, pp. 88-92. 2. Bergman, H. Sambandet mellan neuropsykologiska and datortomografiska fynd hos alkoholpatienter (The relationship between neuropsychological and computer-tomographic findings in alcohol patients). Proeeedings o f the First Malmi~ Symposium o f Ah'ohol 1980, edited by J. Wadstein and B. Sternebring. Malmr: Alkoholklinken, Allmfinna sjukhuset and Ferrosan, 1981, pp. 101-113. 3. Bergman, H., S. Borg, T. Hindmarsh, C.-M. ldestrfm and S. MOtzell. Computed tomography of the brain and neuropsychological assessment of alcoholic patients. In: Bioh~gieal Effects o f Alcohol. edited by H. Begleiter. New York: Plenum, 1980, pp. 771786. 4. Bergman, H., S. Borg, T. Hindmarsh, C.-M. Idestrrm and S. Miitzell. Computed tomography of the brain and neuropsychological assessment of male alcoholic patients. In: Addiction and Brain Damage: Biochemical Aspects o f Dependence and Brain Damage. Proceedings, Symposium on Addiction, Oxford, 1979, edited by D. Richter. London: Croom-Helm, 1980, pp. 201-214. 5. Bergman, H., S. Borg, T. Hindmarsh, C.-M. ldestrrm and S. Miitzell. Computed tomography of the brain and neuropsychological assessment of male alcoholic patients and a random sample from the general male population. In: Alcohol and brain research. Proceedings, second Magnus Huss symposiUm, Stockholm, 5-8 September, 1979, edited by C.-M. Idestrrm. Aeta Psychol Seand Suppl. 286: 77-88, 1980. 6. Bergman, H., S. Borg, T. Hindmarsh, C.-M. Idestrrm and S. Miitzell. Computed tomography of the brain, clinical examination and neuropsychological assessment of a random sample of men from the general population. In: Alcohol and brain research. Proceedings, second Magnus Huss symposium, Stockholm, 5-8 September, 1979, edited by C.-M. Idestrrm. Acta Psyehol S t a n d Suppl. 286: 47-56, 1980. 7. Bergman. H., I. Bergman, K. Engelbrektsson, L. Holm, K. Johannesson and S. Lindberg. Psykologhandboken (Handbook for P.~3'ehoh)gists). Stockholm: Magnus Huss klinik, Karolinska sjukhuset, 1982.

8. Borg, S. The Karolinska project for research and treatment of alcohol dependence (KARTAD): I. Psychiatric aspects. In: Recent Advances in the Study o f Ah'oholism. Proceedings, first Magnus Huss symposium, Stockholm, 1976. Excerpta Medica International Congress Series No. 407, edited by C.-M. IdestrOm. Amsterdam: Excerpta Medica, 1977, pp. 6%74. 9. Damstrrm, K. The Karolinska project for research and treatment of alcohol dependence (KARTAD): III. Sociological aspects. In: Recent Advances in the Study o f Alcoholism. Proceedings, first Magnus Huss symposium, Stockholm, 1976.~ Excerpta Medica International Congress Series No. 407, edited by C.-M. Idestrrm. Amsterdam: Excerpta Medica, 1977, pp. 82-87. 10. Filskov, S. B. and T. J. Boll, editors. Handbook o f Crnieal Nearopsyehology. New York: Wiley, 1981. 11. Myrhed, M. The Karolinska project for research and treatment of alcohol dependence (KARTAD): It. Pharmacological, somatic and laboratory aspects. In: Recent Advances in the Study o f alcoholism. Proceedings, first Magnus Huss symposium, Stockholm, 1976. Excerpta Medica International Congress Series No. 407, edited by C.-M. Idestrrm. Amsterdam: Excerpta Medica, pp. 75-81, 1977. 12. M0tzell, S. Reliabiliteten hos anamnestiska enk/itmetoder frr inneliggande alkoholpatienter (The reliability of anamnestic questionnaires for alcoholic inpatients). Hyg Acta Sot" Med Suet" 87: 310, 1978. 13. Parker, E. S., I. M. Birnbaum, R. A. Boyd and E. P. Noble. Neuropsychological decrement as a function of alcohol intake in male students. Alcoholism: Clin Exp Res 4: 330--334, 1980. 14. Parker, E. S. and E. P. Noble. Alcohol consumption and cognitive functioning in social drinkers. J Stud Alcohol 38: 12241232, 1977. 15. Parsons, O. A. and S. P. Farr. The neuropsychology of alcohol and drug use. In: Handbook o f Clinical Neuropsychology, edited by S. B. Filskov and T. J. Boll. New York: Wiley, 1981. 16. Torgerson, W. S. Theory and Methods o f Sealing. New York: Wiley, 1958. 17. Wilkinson, D. A. and P. L. Carlen. Chronic organic brain syndromes associated with alcoholism: neuropsychological and other aspects. In: Research Advances b~ Ah'ohol and Drug Prablems. edited by Y. Israel, F. B. Glaser, H. Kalant, R. E. Popham and R. G. Smart. New York: Plenum, 1981, pp. 107145.